New Measures for Prolonging the Nozzle Service Life
Yuan Changjun,
Liu Zongchang
Issue:
Volume 5, Issue 2, December 2019
Pages:
30-38
Received:
9 November 2019
Accepted:
28 November 2019
Published:
10 December 2019
Abstract: Microstructures of 27SiMnMoVA steel intended for nozzle in raw, as-brazed and as-normalized states were surveyed by using OLS4000 laser scanning confocal microscope, Axiovert-25CA optical microscope and QUENTA-400 scanning electron microscopy. It is found that the microstructures of raw 27SiMnMoVA steel are ferrite and pearlite; the microstructures of the as-brazed 27SiMnMoVA steel are ferrite, martensite, bainite and troostite; the microstructures of as-normalized 27SiMnMoVA steel are sorbite and bainite; and that the as-normalized microstructures are appreciably finer than the as-brazed microstructures. Adjusting the carburizing and hardening processes, a cryptocrystalline martensite provided with better wear-resistance is obtained in the case of 27SiMnMoVA steel specimen, and the effective hardened depth is increased from 0.48mm to 0.75mm. Retained austenite content and wear-resistance of the 27SiMnMoVA steel specimens in different heat treatment conditions were measured by means of D8 Advance X-ray diffractometer and MM200 Pin-on-Disk wear testing machine. The results show that the retained austenite contents in the specimens are six to eight percent, and the abrasion marks are as about 3mm. The volume and superficial area of the cooling chamber were increased by 13% and 23% respectively by the way of improving it’s structure, which made the cooling performance of the needle nozzle enhanced significantly. The purpose of increasing the flow coefficient of the nozzle spray holes, improving the spray quality and performance of the nozzle and prolonging the nozzle assembly service life were achieved by adopting liquid extrusion grinding process and carried out the liquid extrusion grinding in spray holes of the nozzle by using KYM-2 liquid extrusion grinder.
Abstract: Microstructures of 27SiMnMoVA steel intended for nozzle in raw, as-brazed and as-normalized states were surveyed by using OLS4000 laser scanning confocal microscope, Axiovert-25CA optical microscope and QUENTA-400 scanning electron microscopy. It is found that the microstructures of raw 27SiMnMoVA steel are ferrite and pearlite; the microstructures...
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Quinn’s Law of Fluid Dynamics Pressure-driven Fluid Flow Through Closed Conduits
Issue:
Volume 5, Issue 2, December 2019
Pages:
39-71
Received:
12 October 2019
Accepted:
11 December 2019
Published:
6 January 2020
Abstract: In this paper we develop from first principles a unique law pertaining to the flow of fluids through closed conduits. This law, which we call “Quinn’s Law”, may be described as follows: When fluids are forced to flow through closed conduits under the driving force of a pressure gradient, there is a linear relationship between the fluid-drag normalized dimensionless pressure gradient, PQ, and the normalized dimensionless fluid current, CQ. The relationship is expressed mathematically as: PQ=k1 +k2CQ. This linear relationship remains the same whether the conduit is filled with or devoid of solid obstacles. The law differentiates, however, between a packed and an empty conduit by virtue of the tortuosity of the fluid path, which is seamlessly accommodated within the normalization framework of the law itself. When movement of the fluid is very close to being at rest, i.e., very slow, this relationship has the unique minimum constant value of k1, and as the fluid acceleration increases, it varies with a slope of k2 as a function of normalized fluid current. Quinn’s Law is validated herein by applying it to the data from published classical studies of measured permeability in both packed and empty conduits, as well as to the data generated by home grown experiments performed in the author’s own laboratory.
Abstract: In this paper we develop from first principles a unique law pertaining to the flow of fluids through closed conduits. This law, which we call “Quinn’s Law”, may be described as follows: When fluids are forced to flow through closed conduits under the driving force of a pressure gradient, there is a linear relationship between the fluid-drag normali...
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